Recovery of juices from sugar muds



v Nov. 25, 1947.

J. DlAZ-COMF'AIN RECOVERY OF JUICES FROM SUGAR -MUDS Filed March 2l,1944 Y l Nov. 25, 1947. J. nlAz-coMPAlN RECOVERY OFVJ'UICES FROM SUGARMUDS I 2 Sheets-Sheet 2 Filed March 2l,y 1944 Ql Qu Patented Nov. 25,1947 rse is @Partnr @oer-ics 12,4311534 y Risco'visiti' 10F -JUIoEsIFROMsuene MUDs "Jernimo D'azLColnpain,/Centralisenado,E Cuba rotin-iis)f 114* claims. 41

"This invention "relates to "recovery'oi vjuices :fromsu'gar muds; andit comprises a process of `:treating sugars'cums or mudsj-suc'h as themud "recovered from 'the usual clarifying units or the A'lter cakerecovered from a continuous Yfilter operating onthe cl'arier mud; saidprocess comprising 'alilllying' sucha mud to the bagasse blan-'ketpass'ing through a -pluralit'y of cane grinding millsat-a"pointbetween the nal mill and the yflast Vpoint at Which'anyeniacerationwater is applied to the blanket, 'whereby washing away of f saidlmud'with maeeratio'n water 'is avoided and thesug'ar juice/lcontainedinthe mud is recoil,- ered;isaid process being preferably conducted byvforming twor separate ba'gasse blankets -from 'the 'bagasse passingthrough the mills, introducing "the mud between said Ablankets vandpassing the resulting assembly through a 'final mill to extract juicetherefrom; all as more fully hereinafter set forth and as claimed.

In 'the processor recovering juices from sugar '-.cane the caneislpassed Ythrough a series of crushing or :grinding YVmills.

The crushed cane forms 'what is known'as a'bagasse blanketduring its-passage through `the mills Zand this blanket is Vthereafter used in thefurnaces to produce power for the 4sugar manufacturing operations. Inthe sugar processing operations, which are conducted `in the sugarhouse"-or boiling house, muds or scums areproduced For example theclarifying units -(clarier`s) Aproduce a mud known 1as cacha'za Thesemudsorscumsare conventionally treated for recovery of their sugarValues. Usually -they are passed. to a Vcontinuous rotary vacuum--filter Where `line bagasse, known as bagacill, is used as a lter aid.

Owing to the fact that most sugar cane factories have deficient lheatbalances, that is, heat balances which require fuel in addition to thatsupplied by the ba'gas'se, it is frequently necessary to burn the fmudsor the lter cakes fromthe conventional Vcontinuous lters. The 'mudslrepresent about 3.2 per cent of the total cane and vhence,ifsuiiiciently dehydrated, constitute a valuab-le source of fuel. Butrthe iilter cakes from the usual continuous `filters contain from 'about75 to 85 per cent of moist-ure (Zfper cent sucrose). In contrast thebagasse blanket from the .grinding mills contains only `about v50 percent moisture (3 per cent sucrose). directly to the bagasse blanketbefore the latter is sent to the `furnaces, as i'sfconventional in manysugar factories, the moisture content of the blan- -ket 4is increased'toabout 53.5 per cent, which is,

of course, a decided disadvantage from a fuel standpoint.

It has heretofore been proposed topadd the muds or scums from the sugarhouse to the ybagasse blanket as it is passing through the rst lmil-l.of the series and vprior to. the-mill or `-rxri-l-ls If the muds areadded -jblanket `and has time 'to cool.

supplied with masceration'water. If this p fo- A.practicalto addthe'nludsto-thevbagas'se blanket prior to the maceration Water. AIfthisis done,

the top of-the'bagasse blanket becomes slimy and slippery and thegrinding eiciency is substantially reduced. Moreover the macerationwater, whichkis usually "hot, tends'to dissolve impurities -from themuds and to wash them through the bagasse blanket, 1resulting injucesfofconsiderably lower purity. This increases the clarication diflicultiesand Iresults in an inferior sugar of low keeping quality. V ,n I y Ihave `Adisr'zovneredrthat vthe above difficulties can be avoided byadding'the muds at a point between the nalvmill of the grinding unit andythe last point at whichanyv maceration water is added. If the"maceraton Water is addedk to the blanket prior to the rnuds, it soaksintgthe When the blanket is then passed through the iinal mill, themacera- -tion water squeezed out does not flush over and wash away themuds `or dissolve the` impurities therefrom, as it does when it issprayed on top of the muds. n 'Ihemuds are then dehydrated to a moisturecontent oi about 5G per cent and the jmoisture removed serves asr'e-maceration water in the last mill'to reduce the sucrose content ofthe bagasse blanket. A double advantage is hereby gained. Moreover themuds soak into the'bag'asse blanket and, Ysince they are not contacteddirectly with maceration water, they do not become slimy and slippery.The grinding efciencyv--of the grinding unit is not reduced appreciably.s

It is possible in my new process to apply the muds directly-as theyarereceived `from the boiling house or 'after they have been dehydratedto a certain citent by'rn'eans oi a continuous filter. The viilter 'cakefrom rsuch a lter can be applied to the bagasse 'blanket prior to thelast mill for example. Itis usually advantageous to mix the Vii-lter'cake with -water before applying it to the ba'ga'fsls'e bl'zvt'nk'et.yThe moisture content of the :filter cake, including"themud, is re ziuce`lto about u per cent, Aw-ll'ereby fits fuel value is greatly enhenbed.V

I'ffinaceration'water is applied at the third from "the Vlast millbutVnot at thel'ast Aornext tothe last, thernuds can bey applied to thebagasse blanket 'at the intermediate carrier of thenext to last mill.The-moisture contained'in the muds is `then pressed 'ont in the last minand this serves to "macration vvirater `a vshort time to cool and tosoakthe mud grinding mill.

into the bagasse blanket before the muds are applied thereto.

A more advantageous method of conducting the present invention is toprovide a separate mill for grinding the muds. This mill can be of theconventional two or three-roll type. The bagasse I 4blanket coming fromthe last mill of the usual grinding unit can then be split in sections,one or two sections being directed to the mud grinding mill. The mudscan be applied to one section of the blanket, which can then be passeddirectly through the mill, but preferably a second section of thebagasse blanket is superposed on top of the muds, whereby the muds arecompressed between two bagasse blankets as they are passed through Inthis fashion no liquid can escape from the muds without passing througha bagasse blanket which serves as a highly eflicient filtering medium.The reincorporation of impurities obtained in this fashion is very in ahigher recovery of sucrose, and the muds are dehydrated more efnciently,resulting in a higher j fuel value.

It is evident from the above that, when my method is used, theconventional rotary vacuum filter can be dispensed with. But if it isdesired to employ such a filter, for example, when a filter is alreadyinstalled, it is possible to pass the filter cake to the bagasse blanketdirectly or to mix it with water prior to such passage. mixed with thefilter cake serves as maceration water, resulting in an increasedrecovery of sucrose.

The low-purity juices recovered from the mill which grinds the muds inaccordance with my invention are advantageously recycled as remacerationjuices. They can, of course, be treated specially or disposed of inother ways.

My invention can be explained with somewhat greater accuracy byreference to the accompanyl ing drawing in which the several figuresconstitute flow charts showing three modifications of my process.

In this showing Fig. 1 is a flow chart showing the muds applied at theintermediate carrier of the next to last mili,

Fig. 2v shows the muds applied to the bagasse `blanket between the twofinal mills, while y Fig. 3 shows my preferred process in which the lmuds are introduced between two bagasse blankets passing through a mudgrinding mill.

The processes illustrated in the flow charts of the drawing are believedto be obvious from a In Fig. l, for example,

left side of the figure and the resulting bagasse is passed from mill tomill in the form of a blanket and finally to the furnace (not shown) atthe right side of the figure. :the first two mills is conducted to theboiling house, while that from the last two mills is delivered to thefirst mill for re-maceration Maceration water is added at theintermediate carrier of the second mill, while mud from the boiling Thejuice expressed by house or from the filters is delivered on top of thebagasse blanket at the intermediate carrier of the *next to last mill.

In Fig. 2 the bagasse passesthrough the mills lasbefore but in 'thisgrinding unit maceration' Any water water is added at the next to thelast mill. The muds are therefore added to the bagasse blanket `at apoint between the. last two mills morder to avoid washing away of themud and dissolving of impurities by the maceration water. The juice fromthe last two mills is separated, that from the last mill being deliveredfor re-maceration to the second mill, while that from the next to lastmill is delivered for re-maceration to the first mill.

In Fig. 3 the bagasse passes through the first four mills as before butis divided into two or three sections after leaving the fourth mill. Afifth mud grinding mill is provided, which may be smaller than the othermills. At least one section of the bagasse is passed as a blanket tothis mud grinding mill. The mud from the boiling house is passed to thevacuum filter and the resulting filter cake is first mixed with Waterand then deposited on the bagasse blanket passing to the mud grindingmill. Alternatively the mud may bypass the filter, as indicated bydotted lines in the flow sheet. and be sent directly to the bagasseblanket. Preferably a second section of the bagasse blanket issuperposed on top of the mud applied to the first section, so that themud is enclosed between the two blankets as the assembly is passedthrough the mill. The juice from the next to last mill is used asre-maceration at the first mill. The bagasse blanket and dehydrated mudfrom the mud grinding mill is united with the remaining bagasse from thegrinding unit and sent to the furnace at the right of the figure.

My tests show that my process, as shown in Figs. l and 2, can be appliedto the grinding units in which 22 rolls are employed without anydetectablereduction in grinding efficiency. In the case of thesmaller'units, employing up to 17 rolls, a slight reduction inefficiency is obtained but this is so small that the advantages gainedoutweigh this slight disadvantage. When a separate mud grinding mill isemployed the efficiency of the grinding unit is not affected, while theefficiency of the mud grinding mill is high even when only a singlebagasse blanket is passed through this mill.

It is evident that the process as described has several importantadvantages among which are the following:

1. The mud after being treated by my process has substantially the fuelvalue of the usual bagasse blanket. The total fuel value of the blanketplus mud is sufficient in many cases to produce power in excess of thatrequired in the sugar processing, and this excess power can be employedfor other purposes.

2. The fuel Value of the mud treated by my process is substantiallygreater than that of the 'filter cake, including the mud, which isobtained from the usual vacuum filters.

3. More sucrose is recovered from the boiling house muds than can berecovered with the use of vacuum filters owing to the lower juicecontent (50 per cent moisture) of the mud processed in accordance withthe present invention.

4. Additional sucrose is recovered from the bagasse blanket for thereason thatthe moisture expressed from the muds serves as macerationwater. This is particularly true when the mud is mixed 'with macerationwater before being applied to the bagasse blanket.

5. Sugars and nal molasses of better quality are obtained due tosuperior juice clarification,

since the solids and impurities in the muds adhere to the bagasseblanket.

6. The roll surfaces do not become glossy and slippery because mudsolids remain inside the bagasse blanket and are not contacted with therolls after being washed with maoeration water.

7. The usual rotary vacuum lter can be dispensed with, if desired,resulting in a substantial saving, especially in maintenance.

While I have described what I consider to be the most advantageousembodiments of my invention, it is obvious, of course, that manymodifications can be made in the specic procedures described withoutdeparting from the purview of this invention. The recycling of theexpressed juices to be used for re-maceration can be accomplished inseveral different ways, depending upon how many mills and how many rollsare employed. If a special mud grinding mill is employed, this can belocated at any convenient position with respect to the other mill units.Conventional means can be used for removing bagasse from the bagasseblanket coming from the grinding mill unit, in order to form the blanketor blankets to be used lin the mud grinding mill. And it is possible todeposit the mud or lter cake on one bagasse blanket followed byenclosing this assembly between two additional bagasse blankets. Thebagasse blankets passing to the mud grinding mill may be of the order of4 inches thick while the layer of mud may have a thickness ofapproximately inch. Other modifications of my invention which fallwithin the scope of the following claims will be immediately evident tothose skilled in the art.

What I claim is:

1. In the process of recovering juices from sugar muds, wherein sugarcane is passed through a series of cane grinding mills in the form of abagasse blanket, the step which comprises depositing a sugar mud on saidbagasse blanket before the blanket passes through the last mill of saidseries but subsequent to the application of any maoeration water to saidblanket.

2. The process of claim 1 wherein said mud is applied on said bagasseblanket at the intermediate carrier of a mill receiving no macerationwater, said blanket being then passed through the nal mill.

3. The process of claim 1 wherein maceration water is added to the nextto last mill of the series while the mud is applied to said bagasseblanket at a point between the last two mills.

4. The process of claim 1 wherein said mud is the lter cake from afilter operating on a sugar mud and wherein said lter cake is mixed withmaoeration water prior to deposition on said bagasse blanket.

5. In the process of recovering juices from sugar muds, wherein sugarcane is passed through a series of cane grinding mills in a grindingunit, the cane being formed into a bagasse blanket during said passage,the improvement which comprises dividing the bagasse blanket from saidgrinding unit into at least two sections, passing one of said sectionsin the form of a bagasse blanket through a mud grinding mill anddepositing a sugar mud on said last mentioned bagasse blanket before itpasses through said mud grindmaceration water to the blanket.

6. The process of claim 5 wherein said sugar vmud is cachaza derivedfrom a boiling house clarifier.

'7. The process of claim 5 wherein said sugar mud is a lter cake from afilter operating on a boiling house sugar mud.

8. The process of claim 5 wherein said sugar mud is a filter cake from afilter operating on a boiling house sugar mud and wherein said lter cakeis mixed with maoeration water prior to deposition on said bagasseblanket.

9. In the process of recovering juices from sugar muds, wherein sugarcane is passed through a series of cane grinding mills in a grindingunit, the cane being formed into a bagasse blanket dur-V ing saidpassage, the improvement which comprises dividing said bagasse blanketinto at least two sections, depositing a sugar mud on top of one of saidsections, applying a second section on top of said mud, and then passingthe resulting assembly through a mud grinding mill to express the juicesand any added Water from said mud.

10. The process of claim 9 wherein said sugar mud is cachaza derivedfrom a boiling house clarier.

11. The process of claim 9 wherein said sugar mud is a lter cake from afilter operating on a boiling house sugar mud.

12. The process of claim 9 wherein said sugar mud is a filter cake froma filter operating on a boiling house sugar mud and wherein said filtercake is mixed with maoeration water prior to passage through said mudgrinding mill,

13. The process of claim 9 wherein juices recovered from said mudgrinding mill are used for re-maceration, being passed to a mill infront of a mill receiving maoeration water.

14. In the process of recovering juices from sugar muds, wherein sugarcane is passed through a series of cane grinding mills in a grindingunit, the cane being formed into a bagasse blanket during said passage,the improvement which comprises dividing the bagasse blanket from saidgrinding unit into at least two sections, passing one of said sectionsin the form of a bagasse yblanket through a mud grinding mill,depositing a sugar mud on said last mentioned bagasse blanket before itpasses through said mud grinding mill and subsequent to the applicationof any macerating water to the blanket, and recycling the low-purityjuice recovered from said mud grinding mill as re-maceration juice to amill in front of said mud grinding mill.

JERNIMO DAZ-COMPAIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,266,882 Thomas et al. May 21,1918 1,528,501 Morrisson Mar. 3, 1925 1,688,184 Hartmanns Oct. 16, 19281,824,875 Copp Sept. 29, 1931 1,911,246 Spaulding May 30, 1933 2,027,422Fortier Jan. 14, 1936 2,054,556 Copp Sept. 15, 1936

